This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. In this supplemental study, we will monitor the gene expression and miRNA expression profile of the peripheral blood of these HD monkeys at six months intervals throughout the two budgeted years. While peripheral blood samples have already been collected from some of the HD and WT-monkeys at six and twelve month of age, we propose that continuing blood collection occur at 18, 24, 30 and 36 month of age as described in the proposed study. Once the platform of the genome and miRNA profiling studies is established, continued monitoring of peripheral blood will be performed parallel to the other original HD monkeys'longitudinal studies supported by the parent grant, which include cognitive, behavior evaluation, and noninvasive imaging. We hypothesize that analysis of peripheral blood could reveal unique differential gene expression patterns and unique expression profiles of miRNA, which could be used as an indicator of abnormal biological conditions in HD, thus biomarkers of HD progression could be identified.